We present a formulation of the electron–phonon interaction which applies to the case of two atoms per unit cell. Realistic Born–von Kármán phonons are used and the electron–ion interaction is treated in pseudopotential theory. Detailed numerical results are presented for the specific case of Zn. The electron–phonon function α2(ω)F(ω) which enters the electron self-energy and the superconducting properties is calculated. Associated directional functions which allow a discussion of the anisotropy in the electron–phonon interaction are also given. They are employed in a discussion of the anisotropy that enters the electron–phonon mass renormalization as well as scattering times.